This invention relates to a crimping terminal which is so designed that, when a sheathed wire is pushed in a crimping slot, the conductor (core) of the wire is brought into contact with the crimping terminal without removal of the insulating sheath of the wire.
FIGS. 1(a)-1(c) show a conventional crimping terminal disclosed by U.S. Pat. No. 4,385,794. More specifically, FIG. 1(a) is a perspective view of the crimping terminal, FIG. 1(b) is a sectional view taken along line B--B of FIG. 1(a), and the FIG. 1(c) is a perspective view showing part of a sheathed wire connected to the crimping terminal.
In FIG. 1, reference numeral designates 1 the aforementioned conventional crimping terminal. The crimping terminal 1 is formed by press-machining a piece of thin metal sheet. Its front end portion is an electrical contact section 2 which is engaged with the mating terminal (not shown), and its rear end portion is a wire cramping section 3, and the middle portion between those front and rear end portions is a crimping conductive portion 4. The electrical contact portion 2 is engaged with the mating terminal so that the electrical contact portion 2 is electrically connected with the mating terminal; the wire cramping section 3 has right and left retaining pieces (parts of the walls) 3a, which are bent inwardly to fixedly hold the wire W from above the insulating sheath Wb; and the crimping conductive section 4 is electrically connected to the conductor Wa of the wire W. The wire cramping section 3 is coupled through a first constricted portion 6a to the crimping conductive section 4, and the crimping conductive section 4 is coupled through a second constricted portion 6b to the electrical contact section 2.
The crimping conductive section 4 has a front crimping pieces 10A and a rear crimping piece 10B respectively at the front end and the rear end. Each of the front and rear crimping pieces 10A and 10B has a pair of right and left crimping blades which are confronted with each other, forming a crimping slot 12 in which the conductor of the wire is pushed. The wire cramping section 3, the crimping conductive section 4, and the electrical contact section 2 have a belt-shaped common bottom wall. The crimping conductive section 4 is U-shaped in section, having the bottom wall 7 and a pair of right and left side walls 9 which are formed by bending the right and left edge portions of the bottom wall 7 upwardly. The crimping blades 11 of the crimping pieces 10A and 10B are formed by inwardly bending the front and rear edge portion of the side walls 9. The crimping conductive section 4 has recesses 18 which are formed by pressing on the lines along which the side walls 9 are bent with respect to the bottom wall 7, so that the crimping conductive section is increased in bending rigidity.
The wire W is connected to the crimping terminal 1 as follows: One end portion of the wire W is laid on the rear end portion of the crimping terminal 1 in such a manner that the one end portion of the wire W is in parallel with the rear end portion of the crimping terminal 1. Under this condition the one end portion of the wire W is pushed in the crimping slots 12 of the crimping conductive section 4 from above. In this case, the right and left crimping blades 11 cut the insulating sheath Wb of the wire W, and contact the conductor Wa of the wire W. When the one end portion of the wire W is further pushed in, the conductor Wa is caused to go in between the right and left crimping blades 11, thus being positively held by the right and left crimping blades 11. In this operation, a force is applied to the right and left crimping blades 11 to open the same outwardly.
FIG. 2 shows a crimping terminal 21 which has been disclosed by Japanese Utility Model Unexamined Publication No. 15159/1992. The crimping terminal 21 is also formed by press-machining a piece of thin metal plate. The front end portion of the crimping terminal 21 is an electrical contact section 2 which is connected to the mating terminal, the rear end portion is a wire cramping section 3, and the middle potion between the front and rear end portions is a crimping conductive section 4. The wire cramping section 3 is coupled through a first constricted portion 6a to the crimping conductive section 4, and the crimping conductive section 4 is coupled through a second constricted portion 6b to the electrical contact section 2.
The crimping conductive section 4 is U-shaped in section, having a part of the bottom wall 7 which is extended to the electrical contact section 2 and the wire cramping section 3, and a pair of right and left side walls 9 which are formed by bending the right and left edge portions of the bottom wall 7 upwardly. The side walls 9 of the crimping conductive section 4 are continuous to the side walls of the wire cramping section 3, respectively. The crimping conductive section 4 has a front crimping pieces 10A and a rear crimping piece 10B respectively at the front end and at the rear end. Each of the front and rear crimping pieces 10A and 10B has a pair of right and left crimping blades 11 which are confronted with each other, forming a crimping slot 12 in which the conductor of the wire is pushed. The crimping blades 11 are formed by inwardly bending the front edge portions of the side walls 9. The rear contact piece 10B is formed with a crimping plate 13 which is obtained by cutting and raising the bottom wall 7 of the second constricted portion 6b. The crimping plate 13 comprises right and left crimping blades 13a, and a crimping slot 12 defined by the right and left crimping blades 13a. The right and left upper end portions of the crimping plate 13 are engaged with slots 14 formed in the side walls 9, which prevents the crimping plate from falling down forwardly or backwardly.
In general, a crimping terminal is mass-produced, and a number of crimping terminals are built in a connector housing in such a manner that they are adjacent to one another. Hence, there has been a strong demand for the provision of a crimping terminal which is small in size, and light in weight. In order to decrease the weight of the crimping terminal, it is essential to reduce the thickness of a metal plate which is formed into the crimping terminal. In addition, in order to miniaturize the crimping terminal, it is necessary to decrease the width and the length of the crimping terminal. For instance, in order to decrease the width of the crimping terminal, it is essential to decrease the width of the crimping blades forming the crimping slot.
However, if the thickness of the metal plate, which is used to form the crimping terminal, is decreased, or if the width of the crimping blades is decreased, then the mechanical strength of the crimping blades is decreased, as a result of which, when the wire is pushed in the crimping slot, the right and left crimping blades are opened outwardly.
In view of the foregoing, in the conventional crimping terminal 1 shown in FIG. 1, the crimping blades 11 are formed by bending inwardly the front and rear edge portions of the side walls 9 of the crimping conductive section 4. However, the force which acts on the crimping blades 11 when the wire is pushed in the crimping slots, acts collectively on the junctions (the bent portions) of the side walls and the bottom wall 7. As a result, the side walls 9 are bent outwardly, and accordingly, the crimping blades 11 are bent outwardly (opened). In order to overcome this difficulty, the recesses are formed on the junctions of the side walls 9 and the bottom wall 7; however, the recesses are not so effective in preventing the upper end portions of the side walls 9 from falling down; that is, they are not so effective in preventing the crimping blades 11 from being opened.
In the case of the conventional crimping terminal 21 shown in FIG. 2, the side walls 9 of the crimping conductive section 4 are integrally formed with the side walls (the lower portions of the retaining pieces 3a) of the wire cramping section 3. This feature may prevent the side walls 9 from falling down (bending outwardly). However, since the crimping plate 13 which is obtained by cutting and raising the bottom wall 7 of the first constricted portion 6a is employed as the rear crimping piece 10B, it is necessary to obtain an additional dimension in the bottom wall 7 of the first constricted portion 6a which corresponds to the height of the crimping plate 13, and accordingly it becomes difficult to reduce the dimension between the crimping conductive section 4 and the wire cramping section 3, as a result of which the terminal is unavoidably bulky. Furthermore, the side walls 9 of the crimping conductive section 4 are separated from the crimping plate 13, and therefore the side plates 9 do not sufficiently support the crimping plate 13 laterally. Accordingly, it is impossible to prevent the crimping blades 13a from being opened outwardly.